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P0405 Fault in 2000 Daewoo Lanos: Diagnosis and Repair Solutions

Model: daewoo Fault Code: P0405 Posted: 2006-07-27 02:30

I'm experiencing a persistent P0405 fault on my 2000 Daewoo Lanos with 69,000 miles. The vehicle stalls while driving, requiring frequent towing. I've already replaced the EGR valve, cleaned the throttle body and intake manifold tube, but the issue persists. When I remove the EGR valve, the engine starts but produces excessive noise. Attempting to reinstall it while running causes the engine to immediately stall. I'm unsure whether this is a vacuum or electronic EGR valve—my unit has four pins on top (electrical socket) and two holes at the bottom with one hole having an opening that appears to allow air pressure to open/close the valve, similar in design to the 1997 Pontiac Grand Am SE 2.4L. The dealership recently diagnosed a clogged catalytic converter—either front or rear—but there's no visible smoke from the tailpipe. They charged over $1,000 for this repair, which exceeds the car’s value. I'm skeptical: is P0405 actually linked to catalytic converter failure? Shouldn't there be a specific diagnostic code for that? Are there any cost-effective alternatives to replacing the converters? I’ve tried resetting the EGR valve memory by turning off the engine, disconnecting the valve, then reconnecting it and restarting—this didn’t resolve the issue. I also noticed that without the EGR valve installed, the engine runs with hesitation, noise, and near-stall during acceleration, especially at low speeds (10–15 mph), which has caused significant frustration from other drivers. Any technical insight into whether P0405 is truly related to catalytic converter clogging or if there's another root cause? I’d appreciate any guidance on how to verify the issue with a backpressure test or O2 sensor readings, and whether EGR system issues might be more likely than converter failure.

Related fault codes

P0405

Comments (5)

Anonymous 2006-07-27 09:39

Check the EGR valve type—whether it's vacuum-operated or electronic. If it's electronic, a scan tool is required to relearn the minimum EGR position after installation. A properly functioning EGR system should not cause stalling when installed during operation.

Anonymous 2006-07-27 16:24

Thanks for clarifying—I used an electronic EGR valve with a four-pin electrical connector and two holes at the bottom, one of which has an opening that seems to allow air pressure to actuate it. The design is similar to the 1997 Pontiac Grand Am SE 2.4L. I'm now confident it's an electronic unit, so relearning via scan tool should be necessary before the P0405 code clears.

Anonymous 2006-07-27 16:53

Since it's an electronic EGR valve, a dedicated scan tool is needed to perform a memory reset. Try this sequence: turn off the engine, remove the EGR valve, then turn the key on without starting the engine—hold the throttle at full open for about 30 seconds before reconnecting and attempting to start. This may help reinitialize the EGR position. Some GM-style systems require this step after battery disconnection or power interruption to restore idle stability.

Anonymous 2006-07-29 22:23

I tried the reset procedure, but it didn’t work. The car still stalls when I install the EGR valve while running. Without it, the engine runs but with severe hesitation, noise, and near-stall during acceleration—especially at low speeds (10–15 mph). This has caused frequent honking from other drivers. I finally brought it to a dealership, where they diagnosed clogged catalytic converters (front or rear) due to lack of emissions. However, no smoke is visible from the tailpipe. Is this diagnosis accurate? Does P0405 specifically point to catalytic converter failure—or could there be another underlying issue like a blocked EGR pipe or faulty O2 sensor? Are there any affordable alternatives to full converter replacement?

Anonymous 2006-07-31 15:29

Perform a backpressure test to confirm which catalytic converter is clogged. A reliable scan tool can also analyze oxygen sensor readings to identify the affected converter. Check if an EGR pipe runs from the valve to the intake manifold—this could be blocked, causing elevated pressure and triggering P0405. Daewoo vehicles of this era are known for EGR-related issues; verify whether there's still emissions warranty coverage on the catalytic converters. If so, it may reduce repair costs significantly.